This invention relates to a frame construction for motorcycles and more particularly to an improved light weight, compact highly strong and readily serviceable frame arrangement for vehicles.
Although light weight single rider vehicles such as motorcycles have been the subject of considerable development through the years, their frame constructions have been generally similar throughout their development period. The frame normally consists of a head pipe which is a generally vertically extending tube and which supports the front wheel for its steering movement. Affixed to and extending rearwardly and generally horizontally from the head pipe is one or more main tubes. One or more down tubes also extend downwardly and rearwardly from the head pipe and the down tubes and main tubes generally are joined in some manner at their rearward end in the area where the rider's seat is positioned. The engine and transmission of the vehicle are normally positioned within the area bounded by the main and down tubes and may be supported by one or both of these tubes. It is also the practice to position the fuel tank ahead of the rider's seat and above the main tube. This means that the volume of the fuel tank is substantially diminished because of the proximity to the main tube.
Although it is possible to increase the capacity of the fuel tank by lowering the main tube and connecting it to a lower portion of the head pipe, this can present serious problems since this is a highly stressed area. This is particularly true where the rear wheel is also supported at the juncture between the main and down tubes so that the suspension loading will be transferred to the main tube.
It is, therefore, a principal object of this invention to provide an improved frame construction for a vehicle.
It is another object of this invention to provide an improved frame construction for a vehicle embodying a main tube and in which the fuel tank is positioned above and in proximity to the main tube.
It is a still further object of this invention to provide an improved reinforcing construction for a motorcycle frame that permits lowering of the main tube relative to the head tube or head pipe.
Because of the extremely compact nature of motorcycles, it is very difficult to service the components and still provide a rigid and strong frame. This is because of the location of the engine and transmission in the area normally bounded by the main and down tubes, as aforedescribed.
It is, therefore, a still further object of this invention to provide an improved frame construction for a vehicle which facilitates servicing and removal of the engine and transmission assembly.